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I don't have the 1D4 but with my 5D3, I find that the focus shifts significantly with different types and levels of light. The manual even mentions that fact that you should perform MA for the condition you're gonna shoot at. The problem is usually with indoors lighting where it tends to front focus significantly (right on in normal daylight). In addition, the problem is worse when you are not using single spot focusing. Edit: In your sample pictures, looks like you've got some front focusing going on...the last picture above my post, the girl's shoe closest to the viewer is very sharp.
I recommend that you check the focusing and micro-adjust using the basbetball lighting and use spot or surrounding point focusing and not all points. I would not give up on AI Servo though.